This invention relates to a manually operated trigger type dispenser which is adapted to be detachably attached to a liquid container, comprises a trigger and a cylinder having a pump chamber, said trigger being squeezed to suck up the liquid from the container into the pump chamber and to pressurize the liquid, so as to dispense the liquid. The invention also relates to a method of assembling this manually operated trigger type dispenser, and a spinner for use in the dispenser, which is designed to swirl the liquid pressurized in the pump chamber.
The conventional manually operated trigger type dispenser comprises a dispenser body which is adapted to be detachably attached to the neck of a liquid container. The dispenser body is molded of synthetic resin such as polyethylene, and includes an upper portion and a lower portion. An actuating lever, or a trigger, is swingably pivoted to the upper portion of the dispenser body. The lower portion of the dispenser body is cylindrical, and adapted to be attached to the neck of the liquid container, either directly or by a cap. The lower portion extends from the upper portion, substantially at right angles to upper portion. A cylinder defining a pump chamber is incorporated in the dispenser body. An inlet conduit, which communicates with the pump chamber, is provided within the dispenser body, and has an axis extending vertically. An outlet conduit, which communicates with pump chamber, is provided within the dispenser body.
More specifically, the inlet conduit is formed in the lower portion of the dispenser body and extends almost vertically, whereas the outlet conduit is formed in the upper portion of the dispenser body and extends almost horizontally. Hence, the axes of the inlet and outlet conduits intersect with each other, substantially at right angles.
The cylinder is integrally molded with the upper portion of the dispenser body, and is coaxial with the outlet conduit. A piston is provided within the cylinder and coupled to the trigger. This piston reciprocates in a substantially horizontal direction as the trigger is squeezed and released.
As is disclosed in, for example, U.S. Pat. No. 3,840,157 (Hellenkamp) and U.S. Pat. No. 4,227,650 (McKinney), another trigger type dispenser is known which comprises an upper dispenser body portion having a substantially horizontal, cylindrical portion having an outlet conduit, a cylinder integrally molded with the upper dispenser body portion and extending vertically therefrom, and a piston provided within the cylinder and being able to move up and down. In this dispenser, an inlet conduit is formed within the piston, not in the lower dispenser body portion. Nonetheless, the axis of the cylinder, which is integrally molded with the upper dispenser body portion, intersects at right angles with the axis of the outlet conduit.
As is disclosed in, for example, U.S. Pat. No. 4,371,097 (O'Neil), still another trigger type dispenser is known in which the piston is incorporated in the dispenser body and the cylinder vertically reciprocates along the piston. In this dispenser, the outlet conduit is formed in the upper portion of the dispenser body, whereas the inlet conduit is formed in the lower portion of the dispenser body. A cylindrical portion, whose axis extends at right angles to the axis of the outlet conduit, extends vertically from the upper dispenser body portion.
The cylinder, the piston, the trigger, the cap, and the like--all being main components of any conventional dispenser described above--are made of synthetic resin by injection molding, like the dispenser body.
The molding of the dispenser body of any prior art trigger type dispenser described above is accompanied by the following problems.
Were the dispenser body of a single cylindrical component, it could be easily molded, merely by moving a movable mold with respect to a stationary mold. Actually, however, the dispenser body is a combination of two cylindrical components, extending at right angles to each other, i.e., the upper and lower cylindrical body portions, the upper body portions, the upper body portion and the cylinder, or the upper body portion and the cylindrical portion. Therefore, during the molding process, cores must be moved vertically in the plane perpendicular to the direction in which the movable mold is moved. In other words, the cores must be moved in the direction of arrow Y shown in FIG. 19, or in the direction opposite to arrow Y. Consequently, cavities 202, each for molding a dispenser body, cannot be arranged in more than two rows, spaced apart in the direction of arrow Y, in stationary mold 204, as is shown FIG. 19. No cavities can be formed in that portion of mold 204 which lies between those two portions in which the two rows of cavities 202 are made. The number of dispenser bodies, which can be molded in each injection cycle, is inevitably limited.
The dispenser body is more complex in structure than the other components of the dispenser, such as the piston and the trigger. Molten plastic material is injected into cavities 202 under a high pressure. Nevertheless, the plastic material cannot fill up cavities 202 quickly, because of the complex shape of cavities 202, which increases the injection time. In addition, some time is required to move the cores. As a consequence, the injection cycle is prolonged, making it difficult to massproduce the dispenser body. Furthermore, since the cavities 202 have a complex shape, the movable and stationary molds cannot be manufactured at low cost.
In order to manufacture a trigger type dispenser at low cost, it is necessary not only to produce a simple dispenser body in large quantities, but also to put the dispenser body together with the other components within a short time. The components of the conventional dispenser, such as the trigger, the piston, the cylinder, and the cap, cannot be easily fitted into or coupled with, the dispenser body. Thus, the prior art dispenser cannot be assembled within a sufficiently short time.
Most trigger type dispensers have a return spring which is interposed between the piston and the cylinder. Hence, the piston (or the cylinder, in the dispenser disclosed in U.S. Pat. No. 4,371,097), which is movable, is pushed outward by the return spring, and is separated from the cylinder in some cases. None of the conventional trigger type dispensers have a unit comprising a piston, a cylinder and a return spring--all put together, not separated from one another. As a consequence, the prior art dispensers must be assembled in the same factory, from the first step to the last step. In other words, they cannot be manufactured in a knock-down scheme.
Any type of a trigger type dispenser has a nozzle cap attached to the distal end of the nozzle, and a spinner interposed between the nozzle and the nozzle cap. The spinner used in the conventional dispensers is a bottomed cylinder made of synthetic resin. A recess is cut in the center of the distal-end surface of the spinner. A pair of grooves are cut in the distal-end surface, and extend tangent to the recess. Two through holes are cut in the bottom of the spinner and extend in parallel to the axis of the spinner. These through holes connect the grooves to the fluid passage of the nozzle. An orifice is made in the center of the nozzle cap, and is coaxial with the recess of the spinner.
When the trigger is squeezed, the liquid pressurized within the cylinder flows into the recess of the spinner through the liquid passage, the through holes, and the grooves. Since the grooves extend tangent to the recess, the liquid swirls as it flows from the grooves into the recess, and is collected at the center of the recess, and is dispensed through the orifice of the nozzle cap.
A trigger type dispenser is known, wherein an annular space is provided between the spinner and the inner periphery of the nozzle, instead of forming two through holes in the spinner. This annular space functions as a liquid passage, through which the pressurized liquid flows from the nozzle into the tangential grooves of the spinner.
As has been pointed out, the spinner for use in the prior art trigger type dispensers has a recess extending in the axial direction of the spinner, and two grooves extending tangent to the recess, said recess and said grooves all being cut in the distal-end surface of the spinner. The mold for forming this spinner is equally complicated in structure and cannot be manufactured at low cost. Moreover, during the molding process, the molten material cannot fill up the complex cavity of the mold within a short period of time, making it impossible to manufacture the spinner in large quantities or at low cost.
Another problem is inherent in the conventional trigger type dispensers. The liquid passage of the nozzle is always connected to the orifice communicating with the atmosphere, by the tangential grooves and the recess of the spinner. Therefore, when the trigger is squeezed by mistake, the liquid is likely to leak through the passage of the nozzle and the orifice of the nozzle cap. Even if the trigger has been locked, the liquid passage of the nozzle remains open to the atmosphere, and the liquid remaining in the spinner and the nozzle, will unavoidably leak from the nozzle.